The hot news to come out of Croatia today is that Serious Sam 3: BFE will feature "crazy ass split screen." Translated, that roughly means the PC version does up to four-person split screen in the cooperative campaign and multiplayer modes.
One person gets to play via mouse and keyboard, and three friends can join in using gamepads. Apparently, you guys have been demanding this support on Facebook and the forums; thanks for complaining so we don't have to.
Reasons why local play is better than online, directly from the people working on Serious Sam 3: